That seems odd to me Jenny unless I'm not understanding your post. When I look at those bundles it separates out the ones I already own and has the others pre-checked and totaled up.
Maybe they fixed it so it automatically removes the game you already own now. I'm sure there are a lot of people who bought Silver Earring a long time ago and would like the rest of the games. The same is probably true of their other "Bundleopolis" packs.
When I looked at the prices for the individual games, they were only 40% off. It looked like I had to purchase the entire pack to get the 80% off price. But when I tried to purchase the pack, the checkmark for "purchase as a gift" could not be unchecked and it gave me that message about not being able to buy the pack because I already owned one of the games. It didn't remove Silver Earring automatically the way it apparently did for you.